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<head><meta charset="utf-8"><title>I-prioritize #73420 f32::powi on Windows returns different r · t-compiler/wg-prioritization · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/index.html">t-compiler/wg-prioritization</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html">I-prioritize #73420 f32::powi on Windows returns different r</a></h3>

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<a name="201208931"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201208931" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> triagebot <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201208931">(Jun 17 2020 at 22:31)</a>:</h4>
<p><span class="user-group-mention" data-user-group-id="2403">@WG-prioritization</span> issue <a href="https://github.com/rust-lang/rust/issues/73420">#73420</a> has been requested for prioritization.</p>



<a name="201218911"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201218911" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> DPC <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201218911">(Jun 18 2020 at 01:02)</a>:</h4>
<p>p-high?</p>



<a name="201266172"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266172" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266172">(Jun 18 2020 at 13:20)</a>:</h4>
<p>well I'm not sure if this is <code>P-high</code> it could even be considered as intended behavior</p>



<a name="201266207"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266207" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266207">(Jun 18 2020 at 13:20)</a>:</h4>
<p><span class="user-group-mention" data-user-group-id="2403">@WG-prioritization</span> what others think? what should we do with this one?</p>



<a name="201266455"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266455" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> o0Ignition0o - Jeremy Lempereur <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266455">(Jun 18 2020 at 13:22)</a>:</h4>
<p>+1 <code>I'm guessing that LLVM 10 started using the MSVC implementation of the powi intrinsic, which uses a higher precision for intermediate results. </code> i m not sure we ll even fix it</p>



<a name="201266498"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266498" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266498">(Jun 18 2020 at 13:22)</a>:</h4>
<p>yep</p>



<a name="201266506"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266506" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> o0Ignition0o - Jeremy Lempereur <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266506">(Jun 18 2020 at 13:22)</a>:</h4>
<p>it's actually a good thing, so we might wanna document the change of behavior in 1.45 and move on :)</p>



<a name="201266711"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266711" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266711">(Jun 18 2020 at 13:24)</a>:</h4>
<p>but I understand that as a user seeing a change like this is not great :)</p>



<a name="201266734"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266734" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266734">(Jun 18 2020 at 13:24)</a>:</h4>
<p><span class="user-mention silent" data-user-id="218578">o0Ignition0o - Jeremy Lempereur</span> <a href="#narrow/stream/227806-t-compiler.2Fwg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r/near/201266506">said</a>:</p>
<blockquote>
<p>it's actually a good thing, so we might wanna document the change of behavior in 1.45 and move on :)</p>
</blockquote>
<p>maybe we need something like that</p>



<a name="201266795"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266795" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> DPC <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266795">(Jun 18 2020 at 13:25)</a>:</h4>
<p>ye reading the recent comments, can agree <span aria-label="slight smile" class="emoji emoji-1f642" role="img" title="slight smile">:slight_smile:</span></p>



<a name="201266834"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266834" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266834">(Jun 18 2020 at 13:26)</a>:</h4>
<p>I guess we could nominate this issue to go over it quickly during the meeting</p>



<a name="201266926"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201266926" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201266926">(Jun 18 2020 at 13:26)</a>:</h4>
<p>with the intention of raising awareness of more LLVM 10 changes and to quickly define what to do</p>



<a name="201267125"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201267125" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201267125">(Jun 18 2020 at 13:28)</a>:</h4>
<p>That reminds me that we need to re-discuss reverting LLVM; we have not had a lot of regressions in the crater run or otherwise that seem to be due to llvm bugs</p>



<a name="201268303"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201268303" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201268303">(Jun 18 2020 at 13:36)</a>:</h4>
<p><span class="user-mention" data-user-id="116122">@simulacrum</span> <span aria-label="+1" class="emoji emoji-1f44d" role="img" title="+1">:+1:</span></p>



<a name="201268354"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201268354" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> triagebot <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201268354">(Jun 18 2020 at 13:36)</a>:</h4>
<p><span class="user-group-mention" data-user-group-id="2403">@WG-prioritization</span> <a href="https://github.com/rust-lang/rust/issues/73420">#73420</a> has been nominated for discussion in <code>T-compiler</code> meeting.</p>



<a name="201888380"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize%20%2373420%20f32%3A%3Apowi%20on%20Windows%20returns%20different%20r/near/201888380" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> triagebot <a href="https://rust-lang.github.io/zulip_archive/stream/227806-t-compiler/wg-prioritization/topic/I-prioritize.20.2373420.20f32.3A.3Apowi.20on.20Windows.20returns.20different.20r.html#201888380">(Jun 24 2020 at 18:51)</a>:</h4>
<p>Issue <a href="https://github.com/rust-lang/rust/issues/73420">#73420</a>'s prioritization request has been removed.</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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